In a broken world of the near future, humanity faces a strange new crisis: people who should already be dead are attacking the living. The government hands the problem to a specialized body, the Laboratory of Optics and Neural Analysis, better known as LONA. There, researcher Ao and her apprentice Sango try to solve the mystery by analyzing the brains of the dead. They study the memories left in neural circuits, asking what people think about in their final moments and what they leave behind. The result is a science fiction mystery centered on the human mind.